nga-816: pull latest changes from Piotr

FossilOrigin-Name: 4a42046dbc389b6d347e293894730d54fc4a0da8b0608385eba279be4f408810

vm/nga-816/README.md

@@ -1,4 +1,5 @@
 # retro/816
+
 Port of [RETRO Forth](http://retroforth.org/) created
 by [Charles Childers](https://www.patreon.com/_crc) to 
 [C256 Foenix](https://c256foenix.com/), a retro-computer
@@ -14,4 +15,25 @@ port on [go65c816 emulator](https://github.com/aniou/go65c816)
 (use `retro.ini` parameters file here).
 
 ## obligatory screenshot
-![sample run](Screenshot_20210222_213209.png)  
+
+![sample run](barebones-2021-02-28.png)  
+
+## building
+
+You will need a [64tass](http://tass64.sourceforge.net/) assembler.
+
+## rough edges
+
+* inst_di is somewhat borken - it is very crude and doesn't works
+  with signed values
+
+* currently there are only two devices available: keyboard and
+  standard output
+
+## latest changes
+
+### 2021-02-28
+
+* rename nga.asm to barebones.asm to better reflect  which part
+  of RETRO it corresponds to
+

vm/nga-816/barebones.asm

@@ -216,6 +216,7 @@ mclean1     stz  $0,b,x
             jsr  prints
 
             .sdb MEM_SEGMENT
+            .setal
             ldx  #STACK_DEPTH-2
 prep0       stz  #DSTACK,b,x
             dex

vm/nga-816/build.sh

@@ -1,4 +1,4 @@
 #!/bin/sh
-NAME=nga
+NAME=barebones
 
 64tass -Wall -Wmacro-prefix -Wshadow --verbose-list -o ${NAME}.hex -L ${NAME}.lst --intel-hex --m65816 ${NAME}.asm